The containers for containing liquid contents must be capable of discharging the contents irrespective of the materials forming the containers. Discharging the content is not almost of a problem when the liquids having low viscosity such as water and the like are contained. Discharging the content, however, becomes a serious problem when the content is a highly viscous substance such as mayonnaise or ketchup irrespective of the plastic container or the glass container. Namely, the contents of this kind are not quickly discharged despite the container is tilted. Besides, the contents tend to stay on the container wall and cannot be all recovered. Particularly, the content stays in considerable amounts on the bottom of the container and is not all recovered.
In recent years, there have been proposed various kinds of technical arts for improving sliding properties to viscous substances by forming a liquid film on the surfaces of a formed body such as container or the like (e.g., see patent documents 1 and 2).
According to the above technical arts, the sliding property can be strikingly improved as compared to the cases of adding an additive such as lubricant to the synthetic resin that forms the surface of the formed body, and attention has now been paid thereto.
The present applicant has previously proposed a packing container containing an oil-in-water type emulsified product as represented by a mayonnaise-like food, the container forming an oil film on the inner surface thereof with which the oil-in-water type emulsified product comes in contact (JP-A-2015-151131).
With the above means for improving surface properties by forming the oil film on the surface of the base material, however, the life for of effectively exhibiting the slipping property based on the oil film does not last long. Namely, after the passage of a long period of time, the slipping property decreases and depending upon the cases, the content stays on the surface. This tendency becomes conspicuous particularly when the substance that slides on the surface is an emulsified product and, specifically, a mayonnaise-like food containing little oil.
Further, a patent document 3 is proposing a parting oil comprising liquid fat and oil components, animal and plant waxes, and water, and is describing that upon spraying the parting oil onto the container, the dough can be prevented from adhering on the container at the time of baking breads and cakes.
According to experiments conducted by the present inventors, however, when a liquid film is formed by using the above parting oil, the slipping property improves to some extent without, however, much contributing to lengthening the duration for exhibiting slipping property.